Title of Invention

A DEVICE FOR EFFICIENT AIR POLLUTION CONTROL IN BRICK KILNS

Abstract

A device for efficient air pollution control in brick kilns A device for efficient air pollution control in brick kilns by rectangular chamber with vertical conical ends having equi-sized inlet and outlet vertical central openings characterized in that the said chamber being provided at its centre with one or more vertical swayed fins placed parallel to the outlet end of the chamber in such a manner so as to provide central vertical openings concentric to the inlet and outlet openings, the said chamber being also provided with one or more vertical swayed baffles parallel to the inlet end with the crest being concentric to the inlet and outlet openings and also having vertical side openings, the said chamber also being provided with open able pollutant removal covers.

Full Text

The present invention relates to A Device for Efficient Air Pollution Control in Brick Kilns. The problems of brick kiln industry are closely connected with the issues of sustainable development, energy efficiency and environmental friendliness. The Government of India has notified in its Gazette (Extraordinary, Part II - Section 3 - Sub-section (I), April 3, 1996) that solid particle emissions from the brick kiln should not exceed 750 mg/Nm3. Unfortunately, the brick industry, being in the low capital investment category, can not afford to invest heavy amount on air pollution control measures. Non-compliance to emission standards would exert long term adverse impacts on ecology, public health and hence the overall socio-economic structure. Failure to comply with the above regulation governing pollution standards may result in the closure of the brick industry resulting in shortage of bricks and unemployment. Reference may be made to the available literature (Chemical Engineering Hand Book, IVth Ed., by John H. Perry, McGraw Hill Book Co. N.Y.) where it has been reported that, inertial or mechanical seperation devices are most commonly used for removal of particulate matters from the effluent gases. Such devices, however require electricity and the pressure loss is quite high. For brick kiln industry such devices are totally unsuitable because of non-availability of power and skilled labour. What is needed for brick kilns is a device which is once fitted does not require any maintenance and power. Hitherto known devices for controlling pollution in the Brick Industry do not exist for fixed chimney Bull's Trench Kiln. However following devices are commonly used in thermal and other similar industries for the said purpose. 1. Wet Scrubbers. 2. Fabric Filters. 3. Electrostatic Precipitators. 4.Cyclone separates clerical error. 5. Gravity Settling Chambers. All these devices, except gravity settling chambers are not feasibile for Bull's trench fixed chimney brick kiln due to their high operational and maintenance cost, complexity and electricity requirements. Gravity settling chamber however, offers the advantages of modest construction, simple operation and low pressure drop, but are suitable only for removing particles larger than 50 micron size. Its efficiency is very low for finer particles. In order to improve the efficiency of gravity settling chambers horizontal trays are fixed to shorten the settling path of the particles. The provision of horizontal trays makes cleaning difficult and so they found limited use. In another design of gravity settling chamber, inclined baffles/plates are used. The separation is by impingement as well as settling under the action of gravity. All of known types of gravity settling chambers have very low efficiency for particles smaller than 50 micron. Since most of the troublesome particles have much smaller sizes than 50 micron, so the above designs of gravity settling chambers are unsuitable for brick kilns. The drawbacks of the above referred settling chambers are that they are difficult to clean and maintain. They require power and skilled labour to operate. Their efficiency is low and so they are not found suitable for fixed chimney Bull's trench kiln. The main objective of the present invention is to provide A Device for Efficient Air Pollution Control in Brick Kilns, enabling controlling of emission level of suspended particulate matters including finer particles, thus obviating the drawbacks as detailed above. Another objective of the present invention is to evolve a suitable device to achieve the maximum attainable efficiency at an economical cost . Yet another objective is to provide a device which will be easy to construct and will have the possibility of integrating with the existing fixed chimney brick kilns . In the drawing accompanying this specification figure - l represents sectional top plan of an embodiment of the device of the present invention. Accordingly the present invention provides A Device for Efficient Air Pollution Control in Brick Kilns which comprises a rectangular chamber with vertical conical ends having equi- sized inlet and outlet vertical central openings,Characterisol in that the said chamber being provided at its centre with one or more vertical swayed fins placed at an angle parallel to the outlet end of the chamber in such a manner so as to provide central vertical openings concentric to the inlet and outlet openings, the said chamber being also provided with one or more vertical swayed baffles parallel to the inlet end with the crest being concentric to the inlet and outlet openings and also having vertical side openings, the said chamber also being provided with openable pollutant removal covers. In an embodiment of the present invention, the vertical conical ends may be at an angle in the range of 15-20 degrees. In another embodiment of the present invention, the ratio of the width of the vertical end openings to the width of the chamber may be in the range of 1:4 to 1:6. In yet another embodiment of the present invention, the ratio of the width of the central vertical opening between the fins to the width of the inlet and outlet openings may be in the range of 1.5:1 to 2:1. In still another embodiment of the present invention, the one or more vertical baffles may be placed on either side of the central fins. In still another embodiment of the present invention, the ratio of the width of the vertical side openings of the baffles to the width of the inlet and outlet opening may be in the range Of 0.6:1 to 1:1. The device of the present invention comprises an innovative and cost effective design for the removal of suspended particulate matter from the effluent gas stream by providing swayed baffle walls and fins in such a manner so that the gas stream is made to pass through a zig-zag path so that the travel distance significantly exceeds the actual length of the device, which increases the residence time for particulate matter to settle down without increasing the length of the device any further and finally the exit of relatively clean flue gas from the outlet of the stack takes place. An embodiment of the device of the present invention as shown in figure l of the drawing is described below: The device is divided into four sections, section (l) , section (2) , section (3) and section (4) . These sections are surrounded by outer walls (5). Baffle walls (6) are provided in between section (l) and section (2) . Fin walls (7) are provided between section (2) and section (3) . One or more openable pollutant removel covers (8) also have been provided in the top slab for cleaning of all the sections (l, 2, 3 & 4) of the device. Another set of baffle walls (6) has been provided between section (3) and section (4). The device has been covered with the help of a reinforcement cement concrete slab and floor is provided at the bottom of the device. Inlet (9) and outlet (10) openings have been provided to connect the device between kiln and the chimney. Outer wall (5) of the device is made of brick work in mud mortar. Swayed baffle walls (6) and fin walls (7) also are made of brick work in mud mortar. Floor of the device is made up of bricks below which there is a layer of brick chips. Top of the device is provided with reinforced cement concrete slab. The device of the present invention is novel whose function is based upon slowing down, impingement and directional change of the effluent gases in addition to the action of gravitational force to make the particulate matter to settle down within an economical distance limit. The inventive steps lie in providing a combination of vertical fins and baffle walls strategically placed in the path of the flue gas so as to enhance the residence time and enabling reduction of the flue gas flow rate to cause settling down of the coarser and finer suspended particulate matters. The working of the device of the present invention is described below: Polluted gas laden with particulate matters from the brick kiln enters the device at the inlet (9). Horizontal velocity of the gas reduces significantly once the gas enters the device. This, in turn, leads to conditions favourable for settling of particles under gravity. The gas stream is allowed to impinge on baffle wall (6) close to the inlet (9) and then successively glides along the fins (7) . A set of fin walls (7) helps to guide the flow of gases towards the center of the another baffle wall (6) near the outlet end (10) . The polluted gas stream is thus made to pass through the zig-zag path whose length significantly exceeds the actual length of the device, which results in more residence time being available for particulate matters to settle down without increasing the length of the device any further. Relatively clean and purified flue gas finally exits the outlet (10) of the chamber before it enters the atmosphere through the chimney. The following example is given by way of illustration of the device of present invention and therefore should not be construed to limit the scope of the present invention. EXAMPLE-I Example relates to a Device for Efficient Air Pollution Control in Brick Kilns to show the performance as claimed. The device has been integrated in a fixed chimney brick kiln in the central tunnel just before the chimney. The size of the invented device has been fixed as follows: Length of the Device : 3600 mm Width of the Device : 2400 mm Width of inlet/outlet end openings : 530 mm One set of fins and two baffles have been fixed lengthwise at equal distance from each other. The angle of fins, baffles and vertical conical ends have been taken as 17 degrees. Width of the central vertical opening between the fins has been taken as 900 mm and the width of the vertical side openings of the baffles has been fixed as 500 mm. The outer walls, fins and baffles are made of bricks in mud morter having 230 mm thickness. The top slab with an openable pollutant removal cover has been provided in reinforced cement concrete. The integration of the Device for Efficient Air Pollution Control in Brick Kilns did not show any adverse effect on the normal functioning of the kiln. Pollution monitoring studies were carried out during various intervals of time to find out the effect of atmospheric conditions on the suspended particulate matters concentration in the effluent gases. Suspended particulate matters concentration in the effluent gases has been monitored before and after the device, so that a fair comparison can be made to assess the efficiency of the device. Results of monitoring in terms of suspended particulate matters concentration in the effluent gases, mg/Nm3 , are as follows: (Table Removed) Monitoring studies have revealed that the provision of the invented device reduces suspended particulate matters concentration in the effluent gases to a value much below the prescribed level. The main advantages of the device of the present invention are: - 1. The device is cost effective, simple and can be constructed by the local people using locally available construction materials. 2. No mechanical/electrical equipment is required in the operation, hence operational and maintenance cost is negligible. 3. As the pressure drop offered by the device is insignificant, the device is suitable for brick kilns and other low stack kilns which operates on natural draught system. 4. The device is capable of removing particles much lower than 50 micron size. Hence, the device reduces suspended particulate matter concentration in the effluent gases to a value below the prescribed level. 5. The device is capable of working with the limited driving force generated by the stack that is available at the kiln site. 6. Dry collection of suspended particulate matters by the device reduces the burden of further downstream treatment of the collected matters. These advantages make the device easily and widely acceptable to a vast majority of the brick kiln owners. claim : 1. A device for efficient air pollution control in brick kilns which comprises a rectangular chamber with vertical conical ends having equi-sized inlet and outlet vertical central openings characterized in that the said chamber being provided at its centre with one or more vertical swayed fins placed parallel to the outlet end of the chamber in such a manner so as to provide central vertical openings concentric to the inlet and outlet openings, the said chamber being also provided with one or more vertical swayed baffles parallel to the inlet end with the crest being concentric to the inlet and outlet openings and also having vertical side openings, the said chamber also being provided with openable pollutant removal covers. 2. A device as claimed in claim 1 wherein the vertical conical ends are at an angle in the range of 15-20 degrees. 3. A device as claimed in claims 1 to 2 wherein the ratio of the width of the vertical end openings to the width of the chamber is in the range of 1:4 to 1:6. 4. A device as claimed in claims 1 to 3 wherein the ratio of the width of the central vertical opening between the fins to the width of the inlet and outlet opening is in the range of 1.5:1 to 2:1. 5. A device as claimed in claims 1 to 4 wherein the one or more vertical baffles are placed on either side of the central fins. 6. A device as claimed in claims 1 to 5 wherein the ratio of the width of the vertical side openings of the baffles to the width of the inlet and outlet opening is in the range of 0.6:1 to 1:1. 7. A device for efficient air pollution control in brick kilns substantially as herein described with reference to the example and drawing accompanying this specification.

Documents:

1123-del-1999-abstract.pdf

1123-del-1999-claims.pdf

1123-del-1999-correspondence-others.pdf

1123-del-1999-correspondence-po.pdf

1123-del-1999-description (complete).pdf

1123-del-1999-drawings.pdf

1123-del-1999-form-1.pdf

1123-DEL-1999-Form-19.pdf

1123-del-1999-form-2.pdf